Answer: Taro
Traditionally, Filipinos used wood rather than stone in buildings. The terraces were an exception. Perhaps a thousand years old, they were built of stone. Because of the mountainous terrain, the Cordillera tribes were able to prevent domination by foreign invaders and thus to preserve their own culture.
The Terraces were put on the UNESCO World Heritage List in 1995. The 2,000-year-old Banaue Rice Terraces in the Ifugao province are also a regular tourist fixture, but did not make it onto the UNESCO list due to contamination by modern structures.
Potatoes came from South America originally, maize from Mexico and wheat from the Middle East. Taro is believed to have come from India and South-east Asia.